Hi, Christoph Hellwig resend: + cc lkml
I found regression in v4.0-rc1 caused by this patch: Author: Christoph Hellwig <h...@lst.de> Date: Wed Jan 14 10:42:36 2015 +0100 fs: export inode_to_bdi and use it in favor of mapping->backing_dev_info Test process is following: 2015-02-25 15:50:22: Start 2015-02-25 15:50:22: Linux version:Linux btrfs 4.0.0-rc1_HEAD_c517d838eb7d07bbe9507871fab3931deccff539_ #1 SMP Wed Feb 25 10:59:10 CST 2015 x86_64 x86_64 x86_64 GNU/Linux 2015-02-25 15:50:25: mkfs.btrfs -f /dev/sdb1 2015-02-25 15:50:27: mount /dev/sdb1 /data/ltf/tester 2015-02-25 15:50:28: sysbench --test=fileio --num-threads=1 --file-num=1 --file-block-size=32768 --file-total-size=4G --file-test-mode=seqwr --file-io-mode=sync --file-extra-flags= --file-fsync-freq=0 --file-fsync-end=off --max-requests=131072 2015-02-25 15:51:40: done sysbench Result is following: v3.19-rc1: testcnt=40 average=135.677 range=[132.460,139.130] stdev=1.610 cv=1.19% v4.0-rc1: testcnt=40 average=130.970 range=[127.980,132.050] stdev=1.012 cv=0.77% Then I bisect above case between v3.19-rc1 and v4.0-rc1, and found this patch caused the regresstion. Maybe it is because kernel need more time to call node_to_bdi(), compared with "using inode->i_mapping->backing_dev_info directly" in old code. Is there some way to speed up it(inline, or some access some variant in struct directly, ...)? Thanks Zhaolei -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
